Cardio System Flashcards
(117 cards)
1
Q
What are the primary functions of the cardiovascular system?
A
To pump, transport, and distribute required elements to cells and tissues, and allow exchange of products between cells in different parts of the body.
2
Q
What are the components of the transportation system in the cardiovascular system?
A
The heart, arteries, veins, capillaries, and lymphatic vessels.
3
Q
What type of structure is the heart, and what is its function?
A
The heart is a highly muscularized tube that contracts to move blood through the system.
4
Q
What is the function of arteries?
A
To carry blood away from the heart to the capillaries.
5
Q
Where does material exchange occur in the cardiovascular system?
A
In the capillaries between the vascular bed and surrounding tissues.
6
Q
What is the function of veins?
A
To return blood back to the heart.
7
Q
Where does the lymphatic system arise, and what does it do?
A
It arises in tissue spaces and returns extracellular fluid as lymph to the blood vascular system.
8
Q
What four factors influence the construction of blood vessel walls?
A
- Velocity of blood
- Pressure of blood propulsion
- Volume of blood
- Requirements for pumping, transport, and ion distribution
9
Q
What four morphological features are considered to fulfill the cardiovascular system’s function?
A
- Size of the lumen
- Thickness of the vessel wall
- Resistance and elasticity of the vessel wall
- Specific function of the organ based on mural elements
10
Q
Describe the arterial side of circulation in terms of volume, pressure, and velocity.
A
It carries a low volume of blood under high pressure and high velocity.
11
Q
How does the capillary system handle blood?
A
It carries a large volume of blood at diminished pressure and velocity.
12
Q
How is the venous system characterized in terms of blood movement?
A
It carries a high volume of blood under very low pressure and velocity.
13
Q
What are the three layers of the cardiovascular wall?
A
- Tunica intima
- Tunica media
- Tunica adventitia
14
Q
What are the three divisions of the tunica intima?
A
- Endothelium
- Subendothelial coat
- Internal elastic membrane
15
Q
What type of cells form the endothelium and what are their features?
A
Squamous cells with prominent nuclei that may bulge into the lumen; marginal cytoplasm is hard to observe under a light microscope.
16
Q
What supports the endothelium and separates it from the subendothelial layer?
A
The basement membrane.
17
Q
What does the subendothelial coat consist of?
A
Loose connective tissue, fibroblasts, and some smooth muscle fibers.
18
Q
What is the internal elastic membrane and its function?
A
A condensation of elastic fibers that separates the tunica intima from the tunica media.
19
Q
What are the components of the tunica media?
A
- Smooth muscle cells
- Collagenous fibers
- Elastic fibers
- Fibroblasts
20
Q
How are the smooth muscle cells in the tunica media arranged?
A
In a circular pattern around the lumen.
21
Q
What are nervi vasorum and vasa vasorum, and where are they found?
A
Nerve and blood supply for the vessels, found in the tunica media of large vessels.
22
Q
What is the external elastic membrane, and where is it located?
A
A condensation of elastic fibers located at the junction of the tunica media and tunica adventitia.
23
Q
What is the tunica adventitia made of?
A
Dense fibroelastic connective tissue.
24
Q
Why is it difficult to distinguish the tunica adventitia’s end from surrounding tissue?
A
Because it blends gradually with the surrounding connective tissue.
25
What important structures are found in the tunica adventitia?
Nervi and vasa vasorum.
26
Is the three-layer wall structure present in all blood vessels?
No, the organizational pattern is not always consistent across all vessel types.
27
Which layer is always present in all blood vessels?
The endothelium.
28
What lines the wall of a capillary?
Only the endothelium lines the capillary wall; the other layers are absent.
29
What is the diameter of capillaries in relation to red blood cells?
The diameter is so small that only one red blood cell (RBC) can pass through at a time.
30
What covers the capillary peripherally?
The basement membrane.
31
What is the main feature of continuous capillaries?
They have no interruptions in the continuity of endothelial cells.
32
Where are continuous capillaries typically found?
Muscles, lungs, nervous system, and other organs.
33
What characterizes fenestrated capillaries?
Presence of pores (fenestrae) in endothelial cells, which are covered by a diaphragm.
34
Where are fenestrated capillaries found?
Endocrine glands, intestines, and other organs.
35
Is the basement membrane intact in fenestrated capillaries?
Yes, it is always intact.
36
What are cells that maintain intimate contact with endothelial cells of capillaries called?
Pericapillary or perivascular cells.
37
What types of pericapillary/perivascular cells exist?
* Histiocytes (fixed macrophages)
* Fibroblasts
* Mesenchymal cells
* Mast cells
* Rouget cells
38
What are Rouget cells and what might they be?
They are smooth muscle cells, probably of metarterioles and precapillary sphincters.
39
What is a defining trait of porous capillaries?
Their endothelial pores are not covered by a diaphragm.
40
Where are porous capillaries found?
In the glomerular capillaries of the kidneys.
41
What are sinusoids lined with?
Endothelial or endothelial-like cells called littoral cells.
42
How do sinusoids compare to typical capillaries in shape and permeability?
They are larger, irregular in shape, and more permeable.
43
What features do sinusoids have in terms of structure?
They have many fenestrations without diaphragms and a discontinuous or absent basal lamina.
44
Are all lining cells of sinusoids phagocytic?
No, some are phagocytic, others are not.
45
What’s the difference between sinusoids and sinuses?
Sinuses are similar to sinusoids but are lined only by non-phagocytic cells.
46
Where are sinuses found?
Bone marrow, spleen, lymph nodes, and hemal nodes.
47
What are arterioles?
Very small arteries with narrow lumens and relatively thick walls.
48
What controls the degree of pressure within the arterial system?
The tonus of smooth muscle cells in arteriole walls, regulated by the autonomic nervous system and hormones.
49
What condition results when smooth muscle tonus is abnormally increased?
Hypertension (high blood pressure).
50
What is a large arteriole a continuation of?
A small artery.
51
Describe the tunica intima of a large arteriole.
Consists of endothelium alone or with some connective tissue; internal elastic membrane is present.
52
What makes up the tunica media of a large arteriole?
Circularly arranged smooth muscle fibers; external elastic membrane may or may not be present.
53
How does the tunica adventitia of a large arteriole appear?
As thick as the tunica media, made up of collagenous and elastic fibers.
54
What does a large arteriole branch into?
A small arteriole.
55
How does a small arteriole differ from a large one?
It has a thinner wall, smaller lumen, a very thin internal elastic membrane, only 2–3 layers of small smooth muscle cells, and mainly collagenous fibers in its adventitia.
56
What does a small arteriole continue as?
A precapillary or terminal arteriole.
57
What is the size of the lumen of a terminal arteriole?
About the size of a red blood cell.
58
Is the internal elastic membrane present in terminal arterioles?
Yes.
59
What is the composition of the media and adventitia of a terminal arteriole?
The media has one layer of smooth muscle cells, and it is surrounded by little connective tissue that serves as the tunica adventitia.
60
What replaces the terminal arteriole?
A metarteriole.
61
What replaces the smooth muscle cells in metarterioles?
Perivascular cells or pericytes known as Rouget cells.
62
Do Rouget cells form a continuous coat in metarterioles?
No, they do not.
63
What is the role of arterioles in blood flow regulation?
They act as sphincters controlling blood flow through the thoroughfare channel to the venous side.
64
What are precapillary sphincters?
Capillaries with some smooth muscle cells that regulate blood flow into the capillary bed.
65
What are small and medium arteries also known as?
Muscular or distributing arteries.
66
Give examples of muscular/distributing arteries.
* Renal
* Ulnar
* Brachial
67
What is the structure of the tunica intima in muscular arteries?
It is typical (composed of endothelium and subendothelial connective tissue).
68
What primarily makes up the tunica media of muscular arteries?
Circularly oriented smooth muscle cells.
69
What is the composition of the tunica adventitia in muscular arteries?
It consists of heavy collagenous fibers, some elastic fibers, and contains vasa vasorum and nervi vasorum.
70
Is the external elastic membrane visible in muscular arteries?
Yes, it is often well-defined.
71
What are elastic arteries?
The largest arteries in the body.
72
Provide examples of elastic arteries.
* Aorta
* Common carotid artery
* Pulmonary artery
73
How does the wall thickness of elastic arteries compare to their luminal volume?
They have relatively thin walls compared to their large luminal volume.
74
What is the structure of the tunica intima in elastic arteries?
It is typical, but the internal elastic membrane is not always distinct.
75
What primarily composes the tunica media in elastic arteries?
Large quantities of elastic fibers arranged in a repeating (lamellar) manner.
76
Describe the tunica adventitia of elastic arteries.
It is thin and blends with the surrounding connective tissue.
77
What is the basic structure of venules?
A simple endothelial tube surrounded by loose connective tissue.
78
How do venous capillaries relate to venules?
They form the transition from capillaries to venules.
79
Compare the tunica media and adventitia of venules.
Venules have a thin tunica media and a thick tunica adventitia.
80
What are small and medium veins a continuation of?
Venules.
81
Describe the tunica intima of small and medium veins.
It is thin, made of polygonal endothelial cells with very little subendothelial connective tissue.
82
Is the internal elastic membrane present in small and medium veins?
No, it is absent.
83
What is the composition of the tunica media in these veins?
Smooth muscle cells with few collagenous and elastic fibers.
84
Describe the tunica adventitia of small and medium veins.
It is thicker than the tunica media and forms the bulk of the vessel wall.
85
What special structures are found in many small and medium veins?
Valves.
86
What forms the venous valves?
Invaginations of the tunica intima into the lumen.
87
What are venous valves composed of?
Flattened endothelial cells lining a core of subendothelial connective tissue.
88
In which vessels are venous valves especially prominent?
In vessels located below the level of the heart.
89
How does the tunica intima of large veins compare to smaller veins?
It is thicker and may contain an internal elastic membrane.
90
What is the composition of the tunica media in large veins?
Mainly collagenous and elastic fibers, with reduced or absent smooth muscle cells.
91
What covers the heart?
The heart is covered by the epicardium, which is a mesothelial-covered fibroelastic membrane.
92
What are the three layers of the heart wall?
1. Epicardium
2. Myocardium
3. Endocardium
93
What separates the epicardium from the pericardium?
The pericardial cavity, which is a potential space.
94
What are the three layers of the epicardium?
a. Superficial layer – mesothelium
b. Middle layer – loose connective tissue containing blood vessels, lymphatic vessels, and some nerves
c. Deeper layer – contains larger blood vessels and more fat; continuous with the endomysium of the cardiac muscle
95
Where is fat particularly abundant in the epicardium?
Along the course of the larger coronary vessels.
96
What is the myocardium?
The muscular and thickest part of the heart wall.
97
What does the myocardium consist of?
Ordinary cardiac muscle cells, Purkinje fibers, blood vessels, and nerves.
98
How does the thickness of the endocardium relate to the myocardium?
It varies inversely with the thickness of the myocardium.
99
What are the three layers of the endocardium?
a. Innermost – delicate connective tissue membrane lined with endothelium
b. Middle – thickest layer; dense connective tissue with many elastic fibers, often alternating with collagen fibers
c. Outermost – irregular connective tissue with fat, blood vessels, and Purkinje fibers; continuous with the endomysium of the myocardium
100
What is the cardiac skeleton?
The central supporting structure of the heart, made of dense connective tissue, where muscle fibers and valves attach.
101
What are the components of the cardiac skeleton?
1. Septum membranaceum – fibrous portion of the interventricular septum
2. Trigona fibrosa – fibrous masses with islands of chondroid tissue between arterial foramina and AV canals
3. Annuli fibrosi – fibrous rings surrounding the origins of the aorta, pulmonary artery, and AV canals
102
What is the composition of the annuli fibrosi?
Dense connective tissue with some fat and thin elastic fibers.
103
What is the cardiac skeleton like in different animals?
Ruminants & older animals – bony (os cordis)
Horse & pig – cartilage-like
Dog – true hyaline cartilage
104
What are the three parts of the impulse conducting system?
1. Sino-atrial (S-A) node
2. Atrioventricular (A-V) node
3. Atrioventricular bundle (Bundle of His)
105
What is the S-A node?
A small mass of specialized cardiac muscle fibers in dense fibroelastic connective tissue; the pacemaker of the heart.
106
Where is the S-A node located?
Right wall of the anterior vena cava, at the upper end of the sulcus terminalis.
107
What type of nerve supply does the S-A node receive?
Parasympathetic (slows heart rate) and sympathetic (increases heart rate) fibers.
108
What is the size comparison of nodal fibers to ordinary cardiac muscle fibers?
Nodal fibers are smaller.
109
Where is the A-V node located?
Lower part of the interatrial septum, just above the attachment of the septal cusp of the tricuspid valve.
110
What is the structure of nodal cells in the A-V node?
Cardiac muscle fibers with fewer myofibrils that often cross at right angles with underlying cell fibers.
111
What is the A-V bundle?
A muscle bundle continuous with the A-V node that divides into two branches for the ventricles and connects with Purkinje fibers.
112
What is the appearance of fibers in the Bundle of His?
Narrower and paler than ordinary cardiac muscle fibers.
113
What is the structure of the smallest lymph vessel?
A wall with endothelial lining and a thin layer of connective tissue.
114
What is the diameter range of lymph vessels?
1/5 mm to 1/2 mm.
115
What are the layers of the wall of a lymph vessel?
T. intima: Endothelium and elastic fibers
T. media: Smooth muscle fibers (circular & oblique) and connective tissue with elastic fibers
T. adventitia: Longitudinal and oblique smooth muscle fibers; includes small blood vessels in medium and large lymph vessels
116
Do lymph vessels have valves?
Yes, except the smallest ones. Valves are more numerous and closer together than in veins.
117
Do lymph capillaries have a basement membrane?
No, they lack a surrounding basement membrane unlike blood capillaries.
